Rehabilitation such as repairing, strengthening, retrofitting of structures is one of the major structural engineering tasks in developed countries. It is estimated that such rehabilitation accounts for more than 50% of total spending in the construction industry. This is a problem that is becoming increasingly imminent in developing countries due to aging, poor design or inadequate maintenance of construction structures.
The use of externally-bonded or -attached high strength reinforcement to reinforce a substrate concrete is currently the most popular method for structural rehabilitation, largely due to its ease of handling in construction. Because of the high strength of the reinforcement material, the material may be made relatively thin. As a result, normal mechanical anchors cannot be directly used for bonding the reinforcement onto the substrate concrete. In order to address this problem, the reinforcement is usually attached to the concrete substrate by surface adhesion. However, the adhesive bond between the reinforcement and the substrate concrete is usually relatively weak such that failure is typically caused by breakdown of the bond at the adhesive interface, i.e. debonding failure. Consequently, tensile strength of high strength reinforcing materials cannot be fully realized unless only a small scale of reinforcement is needed. For larger size of construction structures or when a high increase in structure member strength is required, this technology is often ineffective in providing sufficient strength.
Various technologies have been reported with a view to overcome the problem of debonding of a reinforcement member from a substrate or core member of a construction structure. A system called the hybrid-bonded system has been proposed to significantly increase the bonding strength of a reinforcement member with a core substrate. However, the increase in bonding strength usually comes with a significant increase in construction time, cost and labor.
The present invention seeks to provide an improved reinforcement system for use in construction structures, or at least to provide an alternative to the public.